Jenny lives with her fiance, Bill (Mike Doyle), who doesn't know about her working-class Italian heritage and thinks that she's from Maine.

Gerardo SomozaReunion Pictures

The Mira Sorvino who won an Oscar for her full-bodied twist on the hooker-with-a-heart-of-gold type in Woody Allen's Mighty Aphrodite resurfaces in Union Square, a micro-budget indie that calls for a similar brand of New York brassiness.

Sorvino stars as Lucy, a bipolar train wreck whose behavior is as conspicuous as the clack of her fur-lined high-heel boots, but whose awareness of others is virtually nil. When she's first seen stumbling around Manhattan with a half-dozen shopping bags on her arms, barking belligerently into a cellphone, passersby could be forgiven for tossing the crazy woman a quarter.

Co-written and directed by Nancy Savoca, the once-ascendant indie filmmaker responsible for tart comedy-dramas like Dogfight and Household Saints, Union Square takes baby steps toward a comeback after a near decade-long absence. It's more or less a filmed play, set mainly in a loft apartment on Broadway and concerning the relationship between estranged sisters whose neuroses clash like stripes and plaid. The source of their anguish is too neatly defined, but Savoca's ear for dialogue and a pair of electric lead performances give this souped-up one-act some life.

"We gotta forget everything that happened," says Sorvino's Lucy as she drops by her sister Jenny's place unannounced. The "everything" part is revealed slowly, but the two haven't seen or heard from each other in three years — and starting with a clean slate isn't quite as easy as saying, "Presto!"

Played by Tammy Blanchard, Jenny is every bit Lucy's opposite, a prim, repressed wallflower who lives with her fiance, Bill (Mike Doyle), the upper-middle-class owner of an organic foods line. She's the "normal" one — but Jenny has fled so far from her working-class Italian roots that she's thrown herself into yoga and vegetarian cooking and has Bill believing she's from Maine. She doesn't want to be herself, so she might as well act like the person she thinks her future husband wants her to be.

Set in the days leading up to Thanksgiving, Union Square gets a lot of comic mileage out of Sorvino's carnivorous scenery-chewing and Blanchard's aghast reaction shots — the verbal equivalent of one witnessing the other juggle her priceless vases. Lucy smokes and drinks, tells crude jokes, lets her dog sleep on the expensive furniture and snorts helplessly at her sister's natural-food obsession. "That's delicious," she says of Jenny's curry tofu. "The smell doesn't prepare you for the taste."

When the emotional fireworks start popping, however, this sibling relationship turns to an unfortunate glop of sentimentality and pop psychology. Lucy and Jenny may be different strains of crazy, but Savoca and her co-writer, Mary Tobler, draw too clean a line between the sisters and their late mother, who unlocks the film's mysteries like a skeleton key.

There's too much tortured history between Lucy and Jenny to wrap up so swiftly — as if two such wayward souls could ever find peace, together or apart. Then again, Union Square feels like 80 minutes of Savoca dusting off the cobwebs, so it makes sense that she'd extend her characters the same generosity.

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